Power Factor

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dronai

Member
Location
Ca.
If a device draws 960w at 120V, it would draw 8 amps (true power)

But if it has a power factor of .65

Formula is V*I*PF

120*8*.65 = 624 W

My answer when converted to amps should be drawing 12.3A How can I show the math to get these amps ?
 

Smart $

Esteemed Member
Location
Ohio
If a device draws 960w at 120V, it would draw 8 amps (true power)

But if it has a power factor of .65

Formula is V*I*PF

120*8*.65 = 624 W

My answer when converted to amps should be drawing 12.3A How can I show the math to get these amps ?
960W ? 120V ? .65pf = 12.3A
 

Besoeker

Senior Member
Location
UK
If a device draws 960w at 120V, it would draw 8 amps (true power)

But if it has a power factor of .65

Formula is V*I*PF

120*8*.65 = 624 W

My answer when converted to amps should be drawing 12.3A How can I show the math to get these amps ?
I don't know your level of mathematics is so please forgive me if I'm telling you something you already know.
The equation is:

Power = V*I*PF...............(1)
or, same thing the other way round:
V*I*PF = Power...............(2)

One side of the equation equals the other. Like two equal weights on a balance.
Do whatever you like to one side of the balance and do the same thing to the other and you still have balance.
From (2) divide the left hand side by V and PF so these cancel leaving just I
On the right hand side also divide by V and PF you then get Power divided (V*PF)
You thus get:

I = Power/(V*PF)

Which gives you the 12.3A
 

dronai

Member
Location
Ca.
960W ? 120V ? .65pf = 12.3A

Thanks !

I don't know your level of mathematics is so please forgive me if I'm telling you something you already know.
The equation is:

Power = V*I*PF...............(1)
or, same thing the other way round:
V*I*PF = Power...............(2)

One side of the equation equals the other. Like two equal weights on a balance.
Do whatever you like to one side of the balance and do the same thing to the other and you still have balance.
From (2) divide the left hand side by V and PF so these cancel leaving just I
On the right hand side also divide by V and PF you then get Power divided (V*PF)
You thus get:

I = Power/(V*PF)

Which gives you the 12.3A

Thanks, I'm terrible as you can tell. My 13 yr old is already well into algebra
 
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